Cook the pasta. Meanwhile, chop the sun dried tomatoes and put them in a bowl. Crumble the feta cheese with hands into the bowl. Tear the oregano and the spinach leaves and put them in the bowl also. Add the olives and the black pepper. When pasta is done, drain it and put it straight into the bowl. Add the olive oil and the balsamic vinegar and toss everything until pasta is covered with the sauce.